Capacitive Touch Panel with Electrorheological Fluid for Multi-Touch and Tactile Feedback

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Solution Overview

Problem

Existing touch panels, particularly capacitive types, face limitations in recognizing multiple touches and are prone to wrong inputs, with stability issues against impulse noise and slower sensing speeds.

Innovation Solution

A mutual-capacitive touch panel utilizing electrorheological fluid with a driving unit, sensing unit, combining unit, and selecting unit, where the driving unit applies a driving voltage to electrode pairs to change the viscosity of the fluid, providing a clicking sensation and enabling multiple touch recognition through changes in capacitance, while the sensing unit detects inputs with a simplified circuit structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a mutual-capacitive touch panel uses changes in capacitance between upper and lower electrodes to detect touches, then multiple touches can be recognized, but the circuit structure becomes complex and sensing speed decreases

Engineering Contradiction:

Improvemulti-touch recognition capabilityVSAvoidcircuit structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the sensing function from the driving electrodes by applying a sensing signal separately to dedicated sensing electrodes, while driving electrodes only apply driving signals. This separation simplifies the circuit structure by eliminating the need for complex signal processing at driving electrodes, while maintaining multi-touch recognition capability through the dedicated sensing electrode array.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces electrorheological fluid as an intermediary medium between the upper and lower electrode arrays. This fluid provides tactile feedback through viscosity changes while allowing capacitance measurements to pass through, enabling both multi-touch recognition and tactile feedback without direct mechanical contact between electrode arrays, thus simplifying the overall circuit structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a touch panel uses traditional sensing circuits to detect capacitance changes, then touch input can be recognized, but the panel is prone to wrong inputs and unstable against impulse noise

Engineering Contradiction:

Improvetouch input accuracyVSAvoidimpulse noise susceptibility

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a sensing signal to sensing electrodes and uses the output from these electrodes to determine touch input, creating a dedicated feedback path for sensing. This separate feedback path isolates the sensing function from driving operations, reducing noise interference and improving reliability against impulse noise and wrong inputs.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent segments the electrode functions by separating driving electrodes from sensing electrodes. Driving electrodes only apply driving signals to the electrorheological fluid, while sensing electrodes exclusively detect capacitance changes. This functional segmentation reduces cross-interference and improves noise immunity, enhancing reliability.

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If a touch panel provides tactile feedback through electrorheological fluid, then user experience improves, but the circuit structure becomes more complex

Engineering Contradiction:

Improvetactile feedback qualityVSAvoiddriving circuit complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent merges the tactile feedback function into the existing mutual-capacitive sensing structure by using the electrorheological fluid as both the sensing medium and the tactile feedback actuator. The same electrode pairs that detect capacitance changes also provide tactile feedback through viscosity modulation, eliminating the need for separate feedback actuators and simplifying the overall circuit structure.

Inventive Principle:

Principle #5Merging (Combining)

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 solution allows for stable operation against impulse noise, increased sensing speed, and accurate recognition of multiple touches, providing a tactile feedback experience similar to mechanical keypads.

Implementation Method 1

Methodology Applied

Scientific EffectElectrorheological effect: Electrorheological Effect

Implementation Method 2

a mutual-capacitive type touch panel may determine whether there is an input, based on changes in node capacitance caused by occurrence of a touch

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentEP2455842B1Input sensing circuit and touch panel including the same

Publication Date: 2022.11.02 SAMSUNG ELECTRONICS CO LTD

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AI summary

An input sensing device for sensing an input on a touch panel, and touch panel are provided. The input sensing device has a capacitance node and includes a charge pump to which an output signal from a first electrode of the capacitance node is input as a charge source in response to a sensing signal applied through a second electrode of the capacitance node. The input sensing device determines whether there is an input on the touch panel, based on an output voltage of the charge pump.