Touch Input Sensing Reducing Parasitic Capacitance Influence

Solution Overview

Problem

Touch input sensing devices with multiple electrode pads in a matrix structure face complexity and inefficiency due to the influence of parasite capacitance, which affects the measurement of touch input changes and increases noise and power consumption.

Innovation Solution

Applying the same voltage to both ends of the parasite capacitance to eliminate its effect, using a multiplexer to selectively connect electrode pads, and employing a potential control unit to reduce potential differences, allowing only the change in touch capacitance to be measured.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple electrode pads are used in a matrix structure for touch input sensing, then the coverage and detection capability are improved, but the device complexity and power consumption increase due to the influence of parasite capacitance

Engineering Contradiction:

Improvetouch input detection capabilityVSAvoidcircuit complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The electrode pads are divided into two groups: first electrode pads that are selectively connected to the sensing circuit through a multiplexer, and second electrode pads that are connected to a reference potential. This segmentation allows the system to handle multiple electrode pads while maintaining circuit simplicity by processing one group at a time through the multiplexer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A multiplexer is introduced as an intermediary component between the multiple electrode pads and the sensing circuit. The multiplexer selectively connects either a first electrode pad or a second electrode pad to the sensing circuit at different time periods, enabling multiple pads to be sensed using a single sensing circuit without requiring separate circuits for each pad.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple electrode pads are used in a matrix structure for touch input sensing, then the coverage and detection capability are improved, but the power consumption increases due to the influence of parasite capacitance

Engineering Contradiction:

Improvetouch input detection capabilityVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The electrode pads are divided into two groups: first electrode pads that are selectively connected to the sensing circuit through a multiplexer, and second electrode pads that are connected to a reference potential. This segmentation allows the system to handle multiple electrode pads while maintaining circuit simplicity by processing one group at a time through the multiplexer.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sensing operation alternates periodically between first electrode pads and second electrode pads. During different time periods, the multiplexer connects different electrode pads to the sensing circuit, enabling time-multiplexed sensing that reduces power consumption compared to continuously sensing all pads simultaneously.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If parasite capacitance is present in the touch input circuit, then the circuit can be more flexible in layout, but the measurement precision of touch input changes deteriorates due to noise and unknown capacitance values

Engineering Contradiction:

Improvecircuit layout flexibilityVSAvoidtouch capacitance measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

A multiplexer is introduced as an intermediary component between the multiple electrode pads and the sensing circuit. The multiplexer selectively connects either a first electrode pad or a second electrode pad to the sensing circuit at different time periods, enabling multiple pads to be sensed using a single sensing circuit without requiring separate circuits for each pad.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system uses feedback by comparing the sensing results from first electrode pads with those from second electrode pads. The controller analyzes the differences in sensing values between the two groups to accurately detect touch inputs while compensating for the effects of parasite capacitance.

Inventive Principle:

Principle #23Feedback

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

This approach reduces the complexity and increases the efficiency of touch input sensing, enabling accurate detection with fewer errors and lower power consumption even with multiple electrode pads.

Implementation Method 1

the capacitance Cf as an element configuring the 'equivalent capacitance' is generated by forming an electric field between the capacitance Cf and the conductor

Methodology Applied

Scientific EffectElectric field: Electric Field

Implementation Method 2

the parasite capacitance Cp may be a capacitance which is not intently designed and formed between other parts of the electronic device and the electrode pad

Methodology Applied

Scientific EffectParasitic capacitance: Parasitic Capacitance

Data Source

PatentUS9990080B2Touch input sensing method for reducing influence of parasitic capacitance and device therefor

Publication Date: 2018.06.05 SOLOMON SYSTECH SHENZHEN LTD

AI summary

Disclosed is a touch input sensing device comprising: a touch input sensing electrode; a touch sensing unit connected to one point of the touch input sensing electrode to measure a change in a touch capacitance formed by the touch input sensing electrode according to a touch input; a second node included in the touch input sensing device to form a capacitance between the one point and the second node; and a potential control unit for providing a potential value following the potential of the one point to the second node to decrease a potential difference between the one point and the second node.