Capacitive Touch Screen Sensing and Electric Field Detection

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Solution Overview

Problem

Conventional touch screen systems require separate components for capacitive touch screen sensing and electric field sensing, limiting their resolution and increasing cost and size, while also not being able to detect objects at both short and long ranges effectively.

Innovation Solution

A system that integrates capacitive touch screen sensing and electric field sensing using the same components, such as sensing lines and a touch screen processor, which drives electrodes to perform mutual capacitance measurements for capacitive sensing and self-capacitance measurements for electric field sensing, allowing detection of objects at both near and far distances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If separate systems are used for capacitive touch screen sensing and electric field sensing, then both sensing functions can be provided, but device complexity, cost, and size increase

Engineering Contradiction:

Improvesensing function coverageVSAvoidsystem complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines capacitive touch screen sensing and electric field sensing into a single integrated system. The same sensor array and processing circuitry are used to perform both types of sensing operations, eliminating the need for separate systems and reducing overall device complexity while maintaining both sensing capabilities

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sensing system is designed to perform multiple functions using the same components. The sensor array can operate in capacitive mode for touch detection and in electric field mode for longer-range detection, making the system universal and adaptable to different sensing requirements without requiring separate dedicated systems

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Measurement precision

If conventional capacitive touch screen sensing is used, then physical contact detection is achieved, but detection range is limited to near-field only

Engineering Contradiction:

Improvecontact detection accuracyVSAvoiddetection range

Core Design Contradiction:

Measurement precisionVSLength of moving object

Solution Approach 1:

The system dynamically switches between capacitive sensing mode for near-field touch detection and electric field sensing mode for far-field detection. This dynamic operation allows the system to adapt its detection range and method based on the distance to the object, providing both precise contact detection and extended detection capability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the sensing parameters and measurement techniques based on the detection range required. For near-field detection, capacitive measurements are used with specific frequency and amplitude parameters, while for far-field detection, electric field measurements are used with different parameters, allowing the system to extend its effective detection range while maintaining accuracy

Inventive Principle:

Principle #35Parameter changes

3Length of moving object

If longer-range electric field detection systems are used, then detection range is extended, but measurement resolution decreases significantly

Engineering Contradiction:

Improvedetection rangeVSAvoiddetection resolution

Core Design Contradiction:

Length of moving objectVSMeasurement precision

Solution Approach 1:

The patent segments the detection space into near-field and far-field zones and uses different sensing methods optimized for each zone. By segmenting the operational ranges and applying the appropriate sensing technique to each segment, the system maintains high measurement precision in both near-field touch detection and far-field electric field detection without the resolution loss that would occur with a single system

Inventive Principle:

Principle #1Segmentation

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

Enables simultaneous detection of objects at various distances using common components, reducing costs and size, and enabling features like automatic display activation upon approaching users, without the need for physical contact.

Implementation Method 1

capacitive touch screen sensing... mutual capacitance measurements for capacitive sensing

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

electric field sensing... self-capacitance measurements for electric field sensing

Methodology Applied

Scientific EffectElectric field sensing: Electric Field

Data Source

PatentUS8547360B2Capacitive touch screen sensing and electric field sensing for mobile devices and other devices

Publication Date: 2013.10.01 NAT SEMICON CORP

AI summary

A system includes a touch screen having multiple electrodes. The system also includes a processing unit configured to use the electrodes to (i) detect an object contacting the touch screen or within a first distance from the touch screen in a first mode and (ii) detect the object within a second distance from the touch screen in a second mode. The second distance is larger than the first distance. The processing unit can be configured to use the multiple electrodes in the first mode to perform capacitive touch screen sensing. The processing unit can also be configured to use the multiple electrodes in the second mode to perform electric field sensing.