Electrostatic Input Device Palm Detection Control

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Solution Overview

Problem

Touch pads on notebook PCs often experience operation errors due to palm contact, which existing systems struggle to differentiate from fingertip input, leading to inaccurate determinations and errors.

Innovation Solution

An electrostatic input device with a variation detection unit, determination unit, and control unit that inhibits input operations on specific regions of the detection surface for a predetermined period when the palm is detected, using integrated and movement average values of electrostatic capacitance variations to distinguish between fingertip and palm inputs, thereby preventing operation errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If the touch pad size is increased to improve user comfort and reduce palm contact errors, then the area for fingertip operation is improved, but the likelihood of palm contact increases causing operation errors

Engineering Contradiction:

Improvetouch pad areaVSAvoidoperation accuracy

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent changes the parameter of electrostatic capacitance characteristics to distinguish between palm and fingertip contacts. By monitoring capacitance values and their rates of change, the system can identify palm contacts and inhibit them, thus maintaining large touch pad area while preventing operation errors.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the touch pad size is increased, then the ease of operation is improved, but the frequency of palm contact increases causing operation errors

Engineering Contradiction:

Improveoperation convenienceVSAvoidpalm contact interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful effect of palm contact into a useful detection signal. By using electrostatic capacitance sensing, the system detects palm contact characteristics and uses this information to inhibit erroneous operations, thus converting the harmful palm contact into a beneficial detection mechanism.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Device complexity

If determination is performed based only on contact state (area, length), then the device complexity is reduced, but the discrimination accuracy between palm and fingertip decreases

Engineering Contradiction:

Improvedetermination system complexityVSAvoidpalm-fingertip discrimination accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent introduces additional parameters (electrostatic capacitance value and rate of change) beyond simple contact area and length. These additional parameters provide better discrimination between palm and fingertip contacts, improving measurement precision while maintaining reasonable device complexity.

Inventive Principle:

Principle #35Parameter changes

4Measurement precision

If proximity state determination is used instead of contact state, then the discrimination accuracy is improved, but the device complexity increases

Engineering Contradiction:

Improvediscrimination accuracyVSAvoiddetermination system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical contact detection with electrostatic field-based proximity detection. By using electrostatic capacitance sensing, the system can detect both contact and proximity states without complex mechanical structures, achieving high discrimination accuracy with relatively simple implementation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Effectively prevents operation errors caused by palm contact while allowing smooth fingertip operations by accurately differentiating between palm and fingertip inputs, even when variations in electrostatic capacitance are small, and reduces noise influence through average value calculations.

Implementation Method 1

receiving an input operation according to electrostatic capacitances generated between the plurality of electrodes and an object when the object comes close to a detection surface

Methodology Applied

Scientific EffectElectrostatic capacitance: Capacitance

Data Source

PatentUS10175815B2Electrostatic input device

Publication Date: 2019.01.08 ALPS ALPINE CO LTD

AI summary

There is provided an electrostatic input device including a plurality of electrodes, and receiving an input operation according to electrostatic capacitances generated between the plurality of electrodes and an object when the object comes close to a detection surface, the device including a variation detection unit configured to detect variations in the electrostatic capacitances, a determination unit configured to determine whether the object coming close to the detection surface is the fingertip or the palm on the basis of the variations detected by the variation detection unit, and a control unit configured to inhibit reception of an input operation on the detection surface for a predetermined period of time in a case where the determination unit determines that the object coming close to the detection surface is the palm.